This invention relates to the sealing of sound transmission or blocking devices to a user's ear canal and is particularly concerned with a means for insuring that ear plugs not only fit snugly and comfortably but also consistently.
Disposable prior art ear plugs are typically made of either soft elastomeric material or resilient foam, which must be inserted deep into the ear canal to be effective. Perhaps the most common ear plug of this type is a die-cut or tapered cylinder of resilient, slow recovery foam about 5/8 inch (16 mm) long, as shown in U.S. Re. Pat. No. 29,487. A somewhat more sophisticated but significantly more expensive product is the "Pod Plug," in which a straight rubbery stiffener extends from a rubbery dish-shaped member and facilitates its insertion into the ear canal; cf. U.S. Pat. No. 5,188,123. Insertion of either type of plug is complicated by the anatomy of the canal and the fact that the plugs are available in only a few sizes. Since ear plugs are typically used once and then thrown away, it is generally impractical to have them custom made to fit each person. Further, even if reusable, custom made ear plugs are expensive.